Why does my gaming monitor’s frame rate drop when watching Twitch on a second monitor?

Here’s my computer system:

• PNY GeForce GTX 980 4 GB; DVI–DVI connection to ASUS VG248QE 24-inch monitor (Monitor 1).
• PNY GeForce GT 610 2 GB; DVI–DVI connection to ASUS VH238H 23-inch monitor (Monitor 2).
• ASRock Z87M Extreme4 motherboard
• Intel Core i5-4570 3.2 GHz processor BX80646I54570
• 8 GB memory
• 1 TB WD HDD 7200 RPM
• NVIDIA driver version is 368.22.

And here’s my problem:

Monitor 1 is my gaming monitor. Monitor 2 is my browsing monitor. While using Google Chrome to watch a Twitch stream on Monitor 2, Monitor 1 performance will drop anywhere from 15 to 60 frames. Both monitors have been set to 60 Hz refresh rate through the NVIDIA Control Panel utility. I have tried:

• Updating the NVIDIA drivers (resolved issue assigning primary and secondary monitors).
• Uninstalled GeForce Experience (minimal impact; restored, at best, 10 FPS).
• A different browser (no impact).
• Setting processor affinity for the Chrome instance hosting Twitch (no impact).

Any suggestions would be greatly appreciated.